Effective insulation against moisture is required between the bridge structural elements and the vehicular road bed coatings. Accordingly, the concrete surface is customarily coated with bitumen, and upon this coat there will then be bonded a bituminous sealing strip. Finally, a protective layer of poured asphalt and a cover decking layer are usually placed on top of the sealing layer.
As a rule the poured asphalt, which is at a temperature between 220.degree. and 250.degree. C., will be put in place manually. Due to the high temperatures involved road beds made of pure of polymer-modified bitumen cannot be used. The molten cover decking layer of the sealing strips mixes with the poured asphalt by boiling through and thereby softens it.
Thermoplastic polymer sheets, for example based on polyvinyl chloride, have insufficient thermal resistance. Elastomeric sheets have been observed to produce folds due to the heat, and while these folds to a certain extent can be averted by paper covering, these folds result in a slippery layer forming between the concrete slab and the vehicular road bed cover (BITUMEN-TEERE-ASPHALTE-PECHE, 1972, pp 170-5).
Therefore it had previously been proposed to form bituminous sealing strips for sealing bridges the top side of which is laminated with an embossed aluminum sheet (German OLS No. 21 48 448). It is known, however, that aluminum sheets are corroded by condensation salts. And other metal sheets, for instance, of high-grade steel, are very expensive.